Re: [RFC v2 0/4] vmalloc_exec for modules and BPF programs

From: Song Liu
Date: Fri Oct 07 2022 - 20:17:50 EST



+ Luis.
> On Oct 7, 2022, at 4:43 PM, Song Liu <song@xxxxxxxxxx> wrote:
>
> Changes RFC v1 => RFC v2:
> 1. Major rewrite of the logic of vmalloc_exec and vfree_exec. They now
> work fine with BPF programs (patch 1, 2, 4). But module side (patch 3)
> still need some work.
>
> This set is a prototype that allows dynamic kernel text (modules, bpf
> programs, various trampolines, etc.) to share huge pages. The idea is
> similar to Peter's suggestion in [1]. Please refer to each patch for
> more detais.
>
> The ultimate goal is to only host kernel text in 2MB pages (for x86_64).
>
> Please share your comments on this.
>
> Thanks!
>
> [1] https://lore.kernel.org/bpf/Ys6cWUMHO8XwyYgr@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/
> [2] RFC v1: https://lore.kernel.org/linux-mm/20220818224218.2399791-3-song@xxxxxxxxxx/T/
>
> Song Liu (4):
> vmalloc: introduce vmalloc_exec and vfree_exec
> bpf: use vmalloc_exec
> modules, x86: use vmalloc_exec for module core
> vmalloc_exec: share a huge page with kernel text
>
> arch/x86/Kconfig | 1 +
> arch/x86/kernel/alternative.c | 30 +++-
> arch/x86/kernel/module.c | 1 +
> arch/x86/mm/init_64.c | 3 +-
> include/linux/vmalloc.h | 2 +
> kernel/bpf/core.c | 155 ++----------------
> kernel/module/main.c | 23 +--
> kernel/module/strict_rwx.c | 3 -
> kernel/trace/ftrace.c | 3 +-
> mm/nommu.c | 7 +
> mm/vmalloc.c | 296 ++++++++++++++++++++++++++++++++++
> 11 files changed, 358 insertions(+), 166 deletions(-)
>
> --
> 2.30.2